World population evolution - past, present, future
Over the past 60 years, human population has increased exponentially and the world population evolution is continuing to increase at an ever increasing rate. In 1950 the population of Planet Earth was approximately 2.5 billion (which is actually slightly less than the population of just India & China combined today), this has increased rapidly over the years and the estimated global population in 2013 is approximately 7.1 billion - meaning the the world population has almost tripled in just 60 years.
That is not all however though as population growth is forecast to continue expanding at an increasingly exponential rate, by 2100 if there is no change in fertility and growth continues as expected, the world population will be approximately 19.8 billion people. Once again this means that by 2100 the world population will be nearly tripled again.
Of course, just looking at the overall population growth of the Earth doesn't give us the whole picture, we have to go deeper and look at a regional and country level. One of the most fascinating countries in terms of population is the country with the largest population on Earth, China. In 2013, China has a population of 1.34 billion - which makes it one of two countries with a population of 1 billion + (the other being India).
China are an interesting country to analyze due to their one child policy, they have been one of the fastest growing populations in the world with the population going from 550 million to the 1.3 billion of today. However in the 1980's they implemented the one child policy, hoping to slow the population growth. It didn't have as much of an effect early on as they hoped and the population kept growing - however with stricter enforcement the birth rate in China has slowed noticeably, this combined with generally better education and other social factors means that it is likely that the population will peak in around 2025 at 1.42 billion. After this it is likely that the population will begin to drop rapidly as the one child children have one child of their own and by 2100 it is likely that the population of China will be back down to around 740 million, almost halving their population in 75 years.
While this (if it is successful) will be a great success story we now turn our attention to what happens to a country in a similar situation if it doesn't take action on population control. India. 60 years ago it had a population of just 376 million, this has grown exponentially over the years and today has topped 1.2 billion, by 2020 they will have added 1 billion to their population in just 80 years.
While there have been some efforts made to lower the birth rate (such as limiting access to facilities for government employees to those with 2 or fewer children), there has been no determined focus like there has been in China. So India's population growth rate hasn't really slowed and has remained relatively constant over the years. If nothing changes then by the year 2100, India's population with have soared to a massive 2.32 billion people and some projections (constant fertility) but it as high as 2.94 billion. If India do not put some controls on the population then they will be the most populated country on the planet, by quite some margin. Whether they can sustain that level of population remains to be seen.
So we have seen that the two most populated countries in the world are going to change in quite significant ways over the next 90 years. There are obviously many other countries in the world too, lets look at things on a continental level, more specifically, what might be called a rich continent versus one that might be called a poor continent - Europe v Africa.
Taking Europe first, the population currently stands at approximately 600 million people, this has increased from a population of around 450 million in 1950. As you can see this is a much slower increase than the overall world combined. Also based on current trends the population of Europe has now peaked and if things stay as they are then the population of the continent will be begin to decline within the next few years, hitting 306 million by 2100, actually lower than it was in 1950. This is due to a number of reasons, mostly because the richer the country (or in this continent), the lower the birth rate - due to decreased infant mortality, better education about contraceptives among other things. So assuming things stay as they are there should be very few population issues for Europe over the coming years.
Compare that to what is probably fairly considered the poorest continent on the Earth, Africa. It's population chart looks very different to Europe's, especially for the future. The current population of Africa is a little over 1 billion and it has increased rapidly over the last 60 years, in 1950 it was just 225 million making the population change a massive 5 times what it was. The population growth rate is increasing however and if things stay as they are over the next 90 years or so the population will grow a huge amount with estimates putting at around 10.5 billion. This is due to a number of reasons a major one is the lowering of infant mortality without the corresponding drop in birth rate along with the higher population continuing to have a large amount of children.
Hopefully these examples have shown you that while the world population evolution is showing a large increase in population overall, in reality it is a difference between rich and poor countries - with rich countries generally showing a decrease in populations with the poorer countries causing the overall worldwide population increase. As countries become more developed their population increase rate decreases as evidenced by Europe with it's potentially declining population over the next few years. It looks like it is inevitable the the population will increase massively over the next 100 years, it remains to be seen whether we can handle that as a planet however.